Allow set via key

Author: JimBobSquarePants

src/ImageSharp.Web/Commands/CommandCollection.cs

@@ -33,12 +33,13 @@ private CommandCollection(IEqualityComparer<string> comparer)
         public ICollection<string> Keys => this.keys;
 
         /// <summary>
-        /// Gets the command value with the specified key.
+        /// Gets or sets the value associated with the specified key.
         /// </summary>
-        /// <param name="key">The key of the element to get.</param>
+        /// <param name="key">The key of the value to get or set.</param>
         /// <returns>
-        /// The command value with the specified key. If a value with the specified key is not
-        /// found, an exception is thrown.
+        /// The value associated with the specified key. If the specified key is not found,
+        /// a get operation throws a <see cref="KeyNotFoundException"/>, and
+        /// a set operation creates a new element with the specified key.
         /// </returns>
         /// <exception cref="ArgumentNullException"><paramref name="key"/> is null.</exception>
         /// <exception cref="KeyNotFoundException">An element with the specified key does not exist in the collection.</exception>
@@ -53,6 +54,17 @@ private CommandCollection(IEqualityComparer<string> comparer)
 
                 throw new KeyNotFoundException();
             }
+
+            set
+            {
+                if (this.TryGetValue(key, out KeyValuePair<string, string> item))
+                {
+                    this.SetItem(this.IndexOf(item), new(key, value));
+                    return;
+                }
+
+                throw new KeyNotFoundException();
+            }
         }
 
         /// <inheritdoc/>

tests/ImageSharp.Web.Tests/Commands/CommandCollectionTests.cs

@@ -48,6 +48,42 @@ public void CanInsertCommands()
             Assert.Equal(0, collection.IndexOf(kv2));
         }
 
+        [Fact]
+        public void CanSetCommandsViaIndex()
+        {
+            KeyValuePair<string, string> kv1 = new("a", "b");
+            KeyValuePair<string, string> kv2 = new("c", "d");
+            CommandCollection collection = new();
+
+            collection.Add(kv1);
+            Assert.Single(collection);
+            Assert.Equal(0, collection.IndexOf(kv1));
+            Assert.Equal(kv1.Value, collection[kv1.Key]);
+
+            collection[0] = kv2;
+            Assert.Single(collection);
+            Assert.Equal(0, collection.IndexOf(kv2));
+            Assert.Equal(kv2.Value, collection[kv2.Key]);
+        }
+
+        [Fact]
+        public void CanSetCommandsViaKey()
+        {
+            KeyValuePair<string, string> kv1 = new("a", "b");
+            KeyValuePair<string, string> kv2 = new("a", "d");
+            CommandCollection collection = new();
+
+            collection.Add(kv1);
+            Assert.Single(collection);
+            Assert.Equal(0, collection.IndexOf(kv1));
+            Assert.Equal(kv1.Value, collection[kv1.Key]);
+
+            collection[kv1.Key] = kv2.Value;
+            Assert.Single(collection);
+            Assert.Equal(0, collection.IndexOf(kv2));
+            Assert.Equal(kv2.Value, collection[kv2.Key]);
+        }
+
         [Fact]
         public void CanRemoveCommands()
         {